1. Field of the Invention
The present invention relates to a layout of a pixel portion having a light emitting element, an active matrix display device having the pixel portion, and a manufacturing method thereof.
2. Description of the Related Art
A display device having light emitting elements in a pixel portion is formed by using a metal mask to form the light emitting elements of red (R), green (G) and blue (B) are formed separately. In the case where the light emitting elements are formed of low molecular weight materials, for example, the light emitting elements of red (R), green (G) and blue (B) are formed separately by vapor deposition using a metal mask to form a pixel portion which can realize a full color display.
For manufacturing a light emitting element by vapor deposition, there is a manufacturing method of an organic light emitting device in order to achieve a large size and high definition, in which a ratio of a portion corresponding to a light emitting portion on which a light emitting element is deposited and a width of a boundary portion between adjacent light emitting elements is set to be 1:0.5 or more in a vapor deposition mask (metal mask) used when dividing light emitting elements of each color (see Patent Document 1). Patent Document 1 describes that by slightly changing the pattern of a metal mask and a vapor deposition operation, finely patterned pixels are realized and a full color display can be formed without aligning the mask, thus a large display with high definition can be formed more easily.
Further, apertures are formed in a stripe shape in a metal mask as shown in FIG. 2 of Patent Document 1. As shown in FIG. 9A, a pixel portion 10 includes a plurality of pixels 12 which includes regions 11R, 11G, and 11B which form each element of RBG respectively. As shown in FIG. 9B, the regions 11R, 11G, and 11B for forming each of RGB are divided in rectangular shapes by a bank 13 formed of an insulator before vapor deposition, thereby regions of the same color can be deposited commonly in a column direction. In this manner, row directions are divided by the bank 13, therefore, apertures in stripe shapes (slit shapes) that are long in a column direction are formed in a metal mask.
[Patent Document 1]
Japanese Patent Laid-Open No. 2000-68053